A rise action assistance device according to an aspect of the present disclosure is provided with: a myoelectric potential acquirer that acquires a myoelectric value of a sitting user's tibialis anterior muscle, and a myoelectric value of the sitting user's vastus lateralis muscle or a myoelectric value of the sitting user's vastus medialis muscle； an angle acquirer that acquires a bend angle of the sitting user's upper body； a detector circuit that detects a start of a rise action by the user, based on the myoelectric value of the user's tibialis anterior muscle, the myoelectric value of the user's vastus lateralis muscle or the myoelectric value of the user's vastus medialis muscle, and the bend angle of the user's upper body； and an assistor that starts assistance of the rise action after the start of the rise action is detected.
